There is an apparatus employing the Rankine cycle provided with: a transmission mechanism in which an output shaft of an expansion device is coupled to a rotary shaft of an engine via an electromagnetic clutch that can be engaged and disengaged; a passage through which refrigerant supplied to the expansion device bypasses the expansion device; and a bypass valve interposed in the passage (see Patent Document 1). In this apparatus, the expansion device is stopped by switching the bypass valve from a closed state to an open state, and then switching the electromagnetic clutch from an engaged state to a disengaged state. The reason for this is that when the electromagnetic clutch is switched from the engaged state to the disengaged state before the bypass valve is switched from the closed state to the open state, the expansion device is disconnected from the rotary shaft of the engine such that a no-load state is established, and therefore a rotation speed of the expansion device increases rapidly, resulting in over-rotation of the expansion device, which is to be avoided. By switching the bypass valve from the closed state to the open state first, a front-rear differential pressure of the expansion device is reduced such that the electromagnetic clutch is switched from the engaged state to the disengaged state after the rotation speed of the expansion device has decreased sufficiently. As a result, over-rotation of the expansion device is prevented.
Patent Document 1: JP2012-193690A